[39.08] Radar Altimetery Images of Venus HENG-O Region

Ground-based images of Venus made in 1990 demostrated that
it is possible to produce altimetry images with 1km per
pixel near the times of inferior conjunction. Our new images
were made transmitting 12.5 cm wavelength from Arecibo and
receiving at three stations in the Goldstone complex.
Greater sensitivity is now possible using Arecibo's 1 MW
transmitter and improved feed system. An added advantage is
that the Arecibo transmitter can run continuously through
the view period permitting continuous reception at the three
Goldstone sites. Thus, the Doppler resolution in not limited
by the transmit/receive cycles typical of all past
experiments.

As a result of the improved sensitivity, it is now possible
to achieve greater coverage on a given day and extend the
coverage further from inferior conjunction. A series of 10
experiments were planned for the inferior conjunction of
2001 of which 8 were successful. These images were targeted
in areas where improved resolution could provide a better
understanding of the stratigraphy in the more complex
regions. The early observations focused on the area near
Phoebe Regio and the later ones on HENG-O through Ovda
Regio.

We selected the observation from 15 April, 2001 for initial
processing and software development based on its excellent
data quality and the importance of the HENG-O region.
Initial images show that the expected resolution should be
obtained and that the reflectivity images can extend to 20
degrees from the sub-earth point. The new processing
techniques make use of the Magellan altimetry as a starting
point for a recursive solution to the higher resolution DEM.
This procedure also improves the quality of the reflectivity
images.